Decentralized Volt/Var Control Based on Variable Gradient Projection for PMSG-Based Wind Farm

This paper proposes a decentralized Volt/Var control method based on variable gradient projection (VGP) for the permanent magnet synchronous generator (PMSG)-based wind farm (WF). The aim is to achieve a fast Var response of each wind turbine (WT) to depress voltage fluctuations inside the WF caused by the stochastic wind and voltage disturbance of external girds. The gradient projection (GP) method is used in the PMSG-based WF to regulate terminal bus voltage within a feasible range in a fully decentralized manner while the dynamic characteristics of the PMSGs and grid side converters (GSCs) are taken into consideration. Moreover, according to the difference of the available power distribution among the WTs inside the WF, the adaptive and variable gain method is designed for the GP method, which can achieve maximum Var margin of each local WTs during the real-time operation of the WF. With the proposed control method, the PMSG-based WTs are coordinated to achieve near-global optimal performance only with local measurements. The voltage fluctuations of buses are reduced while the Var margin of WT converters is maximized. The WF with 24 x 5 MW WTs is tested in Matlab/Simulink with the real-time fully nonlinear AC power flow environment.